A photo taken on September 11, 2001 by the New York City Police Department as the North Tower collapses, engulfing lower Manhattan in smoke and ash.

(Photo: AP Photo/NYPD, Det. Greg Semendinger)

More than 1,000 people who have lived or worked near ground zero, including first responders, have been diagnosed with a cancer related to the Sept. 11 attacks on the World Trade Center, health officials say.

According to the National Institute for Occupational Safety and Health, 1,140 people have been certified with a WTC-related cancer. And that number is expected to grow, the Daily News reports.

"There are more cases out there, because we just know of the people in our government-funded medical programs, not those who have been treated by their private doctors,” Dr. Jim Melius, chairman of the WTC Responder Medical Program, told the newspaper. “Because of the carcinogens in the air at ground zero, people who were exposed are vulnerable. And with cancer, there is a delay.”

Tina Engel, an oncology nurse at North Shore Hospital’s WTC clinic in Queens, told the paper she identified 12 new cases in the last two months and has another 25 patients whose diagnostic test results are pending.

“The good news is that with new federal funding, I get what I need when I need it for our patients," Engel said. "Their biopsies and scans are turned around in a week. Cancer trumps everything.”

As many as 65,000 people, including first responders, became sick from 9/11 exposure, according to the Centers for Disease Control. A Mount Sinai Medical Center study cited by the Daily News found a 15 percent higher cancer rate among first responders than among people who were not exposed to the toxic air.

Marty Cervellion, a 63-year-old city engineer who spent more than two months at ground zero following the attacks, developed gastroesophageal cancer in 2011.

“It was always in the back of everyone’s mind we were in jeopardy given the contamination down there, but the entire world was calling on you," he told the Daily News. "It felt so good to serve, there was no wanting to escape."